Mechanisms of LbpB-mediated protection from CAPs. Our data support a model in which LbpB/CaHD can protect bacteria from Lf-dervied CAPs through multiple mechanisms. Firstly, LbpB/CaHD can bind to full-length Lf and prevent the proteolytic release of Lf(17–41) (top row). Additionally, if Lf(17–41) and potentially other CAPs (i.e. LL37) are released, LbpB/CaHD can sequester the CAPs in phase-separated droplets (bottom rows). Multivalency in this system may be achieved in a model in which the helices of CaHD are in a globular bundle, and CAP-binding shields repulsive charges and allows coacervation to occur (model 1). Alternatively, if the helices of CaHD may become extended upon CAP binding and allow for multivalent interactions to form (model 2).